As described in commonly owned U.S. Pat. Nos. 4,974,886 and 5,106,135 a motor-vehicle door latch for use on a vehicle door having a handle and a locking element has a housing, a latch fork pivotal on the housing and engageable in a locking position with a door bolt to retain same and lock the door, an operating lever pivoted on the housing and connected to the handle, a locking lever pivoted on the housing and connected to the respective locking element, and an actuating lever operatively engageable with the fork to release same from the locking position. A link coupled to the locking lever is displaceable thereby between a position coupling the operating lever to the actuating lever for displacement of the fork out of the locking position by actuation of the operating lever and a position decoupling the operating lever from the actuating lever. Thus in the decoupling position actuation of the operating lever will not unlock the door. A central actuator in the latch can displace an antitheft lever into an antitheft position thereof and a mechanism between the antitheft lever and the link decouples the locking lever from the actuating lever in the antitheft position of the antitheft lever so that in the antitheft position actuation of the inside lever will not be able to release the fork.
Typically such a latch is provided with a separate actuator constituted as an electric motor with a rotary threaded output spindle on which is threaded an actuator nut on which is carried a slide. A ratchet-style connection between the slide and the nut allows them to move relative to each other so that in an emergency, for instance when the vehicle battery fails, the latch can be unlocked manually by means of the door key. Such manual actuation forcibly displaces the slider on the nut. In order to reset such a lock, it is therefore necessary that the motor has enough torque to overcome the ratcheting of the slider/nut connection. Hence a relatively strong motor must be used. This increases the size and manufacturing cost of such a latch.